In the preparation of silicon devices, more particularly non-electronic devices, there is a need to remove surface damage on the silicon wafers used in device preparation. Mechanical and/or chemical polishing techniques are used to remove these surface damages. However, surfaces may be damaged as a result of polishing. It becomes necessary therefore to inspect the surfaces for damages after polishing and prior to device fabrication.
These surface damages, in the case of non-electronic applications such as ink jet nozzles, can lead to devices having poorly defined geometries. For example, in the fabrication of ink jet nozzles it is desired to obtain square holes upon etching. Surface damages, however, can cause the holes to be of different geometries, e.g., elliptical, rectangular etc. Additionally, these surface damages can cause scalloping on the walls of the ink jet nozzle where smooth walls are desired. Non-uniformity in hole sizes also arise as a result of these surface damages. In the case of electronic applications these surface damages cause reduced yields, increased shorts, non-uniformity in electrical properties and variations in dielectric breakdown thresholds.
Methods using etchants to detect dislocations and other lattice defects are known. Etchants used for such purpose are described in the publication to F. Secco d'Aragona entitled "Dislocation Etch for (100) Planes in Silicon", J. Electrochem. Soc. Solid-State Science and Technology p. 945, July 1972. The reference teaches the use of an alkali dichromate and hydrofluoric acid etch for revealing dislocation and other lattice defects in (100) planes of silicon. Similarly, the reference to D. C. Schimmel entitled "A Comparison of Chemical Etches for Revealing &lt;100&gt; Silicon Crystal Defects", J. Electrochem. Soc. Solid-State Science and Technology, p. 734, May 1976 compares the effect of etchants and their abilities to detect dislocations and other lattice defects. Specifically etchants such as the Chromate-HF of the above reference and variants thereof and HF--HNO.sub.3 and variants, are considered. Non of these references are concerned with the detection of non-structural defects caused by polishing the surfaces of silicon wafers.